Bonding bearing alloy having high tin content to steel support and bearing

ABSTRACT

BEARINGS HAVING A LAMINAR STRUCTURE COMPRISING A STEEL SUPPORT LAYER AND A BEARING ALLOY LAYER ARE PRODUCED. LIGHT METAL HETEROGENEOUS BEARING ALLOYS CONTAINING IN EXCESS OF ABOUT 7% TIN ARE INVESTED IN A LIGHT METAL IMPERVIOUS TO MOLTEN TIN, SUCH AS ALUMINUM. THE INVESTED BEARING ALLOY IS THEN BONDED TO A STEEL SUPPORT BY HEAT AND PRESSURE WITHOUT EMERGENCE OF TIN FROM THE BEARING ALLOY.

1 FRIEDRICH-WILHELM RABENAU ETAL 3,561,101

BONDING BEARING ALLOY HAVING TIN CONTENT TO STEEL SUPPORT AND BEARING Filed Jan. 20. 1967 United States Patent Oflice BONDING BEARING ALLOY HAVING HIGH TIN CONTENT TO STEEL SUPPORT AND BEARING Friedrich-Wilhelm Rabenau and Erich Jiiger, Neckarsulm,

Germany, assignors to Karl Schmidt G.m.b.H., N eckarsulm, Germany, a corporation of Germany Filed Jan. 20, 1967, Ser. No. 610,669 Claims priority, application Germany, Jan. 25, 1966, Sch 38,374 Int. Cl. B23k 31/02 US. Cl. 29-4975 8 Claims ABSTRACT OF THE DISCLOSURE Bearings having a laminar structure comprising a steel support layer and a bearing alloy layer are produced. Light metal heterogeneous bearing alloys containing in excess of about 7% tin are invested in a light metal impervious to molten tin, such as aluminum. The invested bearing alloy is then bonded to a steel support by heat and pressure without emergence of tin from the bearing alloy.

FIELD OF INVENTION The invention relates to laminating steel and light metal alloys, preferably those having a high tin content, especially for the manufacture of friction bearings. These bearing alloys are heterogeneous in that they contain free tin.

Several processes are known for laminating light metal alloys to steel by rolling, including continuous processes. For example, it has been proposed that, after appropriate surface treatment, the steel be sandwiched in the cold stat-e together with a light-metal band and that the sandwich be heated to 350 to 550 C., and then squeezed between rolls to bond the metals together, the steel being reduced by about 40% and the light metal by about 60% in thickness. In another process, the steel band is heated in an inert gas atmosphere to 550-750 C. and laminated by rolling the steel band and a light metal band, which is in the cold state, the steel remaining practically unreduced in thickness, and the light metal drawing heat from the steel and being reduced -by 50 to 60%. The light metal band is brought to the rolls together with the steel band, and is heated by thermal conduction and radiation on the way to the roller throat to a temperature of 490 C. These processes cannot be used for light-metal alloys having tin contents above 7%, because under the effect of time, temperature and deformation, the molten tin is squeezed out of the heterogeneous alloy and any kind of bonding is forestalled.

SUMMARY OF TI-IE INVENTION According to the invention, the laminating of steel and heterogenous light metal bearing alloy containing over 7% tin, by application of heat and pressure, is facilitated by investing the 'bearing alloy with a light metal impervious to tin at the bonding temperature, and which is adhesive to steel in response to the bonding temperature and pressure. Following this investing, the bearing alloy is bonded to the steel by application of heat and pressure to efiect the adherence. The bonding can be carried out by the known roll-bonding procedure.

It is proposed according to the invention to prevent molten tin from being squeezed out of the bearing alloy that is applied at a rolling temperature which is above the solidus of the bearing tin and is about 400 to 500 C., by first applying to both sides of the heterogeneous bearing alloy, before the cast ingot thereof is rolled, aluminum (i.e. pure aluminum) or a homogeneous aluminum alloy which remains fully ductile throughout all the stresses of further laminating operations. This is done by rough- 3,561,101 Patented Feb. 9, 1971 ening, by for example, wirebrushing, both sides of the bearing alloy, which is about 4 to 10 mm. thick, wrapping it in a likewise wire-brushed or otherwise roughened aluminum or aluminum alloy sheet having a thickness of about 10-25% of the thickness of the bearing alloy, and then laminating this sandwich together in a rolling procedure in which the first pass is desirably as heavy as possible, achieving for example at least a 35% reduction while the remaining passes total more than of the original thickness. The number of passes utilized for this 75% reduction amounts up to 6 to 8.

The aluminum or aluminum alloy investment enveloping the heterogeneous bearing alloy must be of such dimensions that even at the high laminating temperature of 400 to 500 C., the pressure produced by the laminating will not squeeze out any tin droplets. This can be achieved either by using a very thick pure aluminum investment for example 0.1 to 0.15 mm. or by using an aluminum alloy investment that has a high yield point and good roll-laminating qualities, such as, for example, Al-Mn, Al-Mg and Al-Mg-Si. The higher the yield point of the investment material is, the thinner the investment can be.

It is most desirable to envelop the bearing metal in an investment material consisting of a suitable alloy, preferably a commercially available duralumin (Al-Cu-Mg alloy) sheet material, clad with aluminum, since, when the aluminum surface is wirebrushed, it establishes an excellent bond with the wirebrushed or otherwise roughened bearing alloy in the rolling process. This procedure furthermore has the advantage that, in the final rolling of the bearing material onto the steel, the roughened steel comes into direct contact with the pure aluminum and an excellent bond is produced between them even by relatively light rolling.

The method of the invention in its preferred form involves the use of a very ductile and tough, prelaminated investment lamina of at least about 0.15 mm. thickness and that stands up extraordinarily well to the operation of laminating it to the steel. The investment lamina, when bonded to the bearing alloy, has a yield point of at least 10 kp./mm. This cladding either has to be especially thick in the case of aluminum and low-alloy aluminum investments, or may be thinner in the case of investments having a high yield point, as in the case, for example, of an investment made of Duralplat, an aluminum-coppermagnesium alloy coated on all sides with aluminum.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is depicted diagrammatically in the figures, in which:

FIG. 1 is a side elevation view of a laminate comprising an invested bearing metal strip applied to a steel support;

FIG. 2 is a showing of a portion of a bearing formed from the laminate shown in FIG. 1;

FIG. 3 and FIG. 4 correspond respectively, to FIG. 1 and FIG. 2, and show an alternative construction.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows an laminated bearing material, 1 representing the steel support which has been laminated to the heterogeneous bearing alloy 3 which is covered on both sides by layers 2 and 4, which are composed of ductile, homogeneous light-metal investment alloy. This material is used to form a bearing half as shown in part in FIG. 2. After the forming of the bearing, the inner stratum of investment material 4 and, if desired, the outer steel material 1 are machined down to provide the thickness S so that no traces of the investment material remain on the inner bearing surface.

In FIG. 3 there is shown a laminated bearing material in which the bearing alloy material 5 has also been bonded to the steel support 1, and is enveloped in an especially ductile duralumin alloy (3, 7) which is coated with pure aluminum (2, 4, 6, 8). After the bearing material has been formed into a bearing half as in FIG. 4, the investment material (6, 7, 8) bonded to the inside of the bearing is machined down to the wall thickness S, so that the inner friction surface 5 0f the bearing consists of the pure heterogeneous bearing alloy and the outer supporting material 1 consists of steel.

EXAMPLE A bearing alloy containing 20% tin and 80% aluminum is cast into 20 mm. ingots and cold-rolled to a thickness of 8 mm. Then the surface of this rolled strip is prepared by wire-brushing, scouring or etching for the laminating process. A matching strip of aluminum, aluminum alloy or aluminum-copper-magnesium alloy coated with aluminum (Duralplat) is likewise brushed bright and closely wrapped about a strip of bearing alloy. Then the alloy ingot thus wrapped is heavily reduced in a single pass through the rolls by 36 to 46%, to a thickness between 4.8 and 5.6 mm., and it is then rolled in a number of additional passes down to a thickness of 1 to 2 mm. For this reduction about 10 passes are utilized by coldrolling.

The ribbon of invested bearing alloy thus prepared is cleaned by wire-brushing, scouring or etching, and then delivered in the cold state into the roll gap through which the steel ribbon, which has been roughened and heated inductively to 550-720" C. under inert gas, is simultaneously passed. In the roll gap, the invested bearing alloy strip is briefiy heated to 490 C. and bonds to the heatyielding steel under the influence of pressure and temperature. The rolling is conventional.

The cross-sectional reduction during laminating to the steel of the light metal alloy must be such as to achieve the greatest possible adhesion by the slightest possible deformation (25 to 50%). The amount of deformation required depends in turn on the seizing tendency of the light metal covering the bearing alloy, and it is lowest when pure aluminum is used as the investing metal. The thickness of the investment depends in turn on the extra machining allowance prescribed for the further working of the bearing material. The two must be coordinated so as to assure in every case that the surface of the finished bearing will contain no traces of the investment material.

While the invention has been described with respect to particular embodiments thereof, these embodiments are really representative and do not serve to define limits of the invention.

What is claimed is:

1. In a process for laminating steel and heterogeneous light metal bearing alloy containing over 7% tin by application of heat and pressure to bond the bearing alloy to the steel, the improvement which comprises investing the bearing alloy with an aluminum alloy impervious to tin 4 at the bonding temperature and adhesive to steel in response to the bonding temperature and pressure, and thereafter, by rolling, bonding the bearing alloy to the steel at a rolling temperature above the solidus of the bearing tin to cause the investing metal to adhere to the steel.

2. Process according to claim 1, wherein the investing metal is aluminum, aluminum alloy, or aluminum clad alloy.

3. Process according to claim 2, wherein the investing metal is an aluminum alloy of the group Al-Mn-Mg, Al-Mg, and Al-Mg-Si.

4. Process according to claim 1, said rolling temperature being about 400500 C.

'5. In a process for laminating steel and heterogeneous light metal bearing alloy containing over 7% tin by application of heat and pressure to bond the bearing alloy to the steel, the improvement which comprises investing the bearing alloy with an aluminum alloy impervious to tin at the bonding temperature and clad with aluminum on a surface thereof exposed following said investing, toughening the exposed surface of the aluminum cladding and an exposed surface of the steel, and, by rolling, bonding the roughened surfaces at a rolling temperature above the solidus of the bearing tin to cause the aluminum cladding to adhere to the steel.

6. Process according to claim 5, wherein the investing metal is an Al-Cu-Mg alloy.

7. Process according to claim 5, said rolling temperature being about 400500 C.

8. In a process for laminating steel and heterogeneous light metal bearing alloy containing over 7% tin by application of heat and pressure to bond the bearing alloy to the steel, the improvement which comprises investing the bearing alloy with an Al-Cu-Mg alloy clad with pure aluminum, impervious to tin at the bonding temperature and adhesive to steel in response to the bonding temperature and pressure, and thereafter bonding the bearing alloy to the steel with said cladding in contact with the steel, by application of heat and pressure to cause the investing metal to adhere to the steel, the bonding temperature being above the solidus of the bearing tin.

References Cited UNITED STATES PATENTS 1,940,850 12/1933 Derby 294723 2,484,118 10/1949 Reynolds 29492 2,879,587 3/1959 Mushovic et al. 29504X 3,096,577 7 1963 Carlson et al. 29492X 3,132,418 5/1964 Fulford 29472.3X 3,195,991 7/1965 Stern et al. 29492X JOHN F. CAMPBELL, Primary Examiner R. J. SHORE, Assistant Examiner U.S. Cl. X.R. 29498, 504 

